" As I remember, a twin cylinder engine had two pistons, rods, and shared
the same combustion chamber, while a two cylinder engine had separate
combustion chambers. I am probably remembering wrong, but know there
was a distinct difference."

I think you have it nailed. I had one of those (about 40 years ago, come to
think of it) in a motorcyhcle. It had 2 cylinders firing simultaneously
under a common head. I remember the definition of that configuration as
being "twin cylinder".

Bob Swinney



wrote in message
ups.com...
More than 40 years ago I had an automotive encyclopedia that gave good
definitions for both two cylinder engins and twin cylinder engines. I
loaned the book and never got it back.


I have Googled all the ways I can think of, but cannot find a
definition for a "twin cylinder" engine. Seems like the names have
become interchangable. Does anyone have a documented source for the
definition of the "twin cylinder" engine?

This has been driving me crazy for years.

Thanks,
Paul in Redmond, OR